I'll address the RO first because it's the easy one. If your raw water TDS is 380 and the water guy got 600 on your RO water, there are a couple of possibilities. Either: The water guy failed to calibrate his TDS meter so the number is wrong. The water guy deliberately took a sample of the RO waste water in order to drum up more business. The effluent and waste water line from your RO are reversed. Any of these cases should tell your guy doesn't know much about RO. Softener: When we size a softener with water and salt usage in mind, we look for that sweet spot where regen occurs about once per week to keep water usage reasonable and regen with between 6 - 8 lb salt per cubic ft of resin to obtain good softening with reasonable salt usage. In your case, the city reports a range of hardness. In order assure you never have a hardness spike, we need to size for the maximum of 26 gpg. The best size for salt and water efficiency would be a 2.5 cubic ft softener. It would regen every 7 days and use 63 lb salt per month. If you choose a 2.0 cubic ft softener instead, you could still regen evey 7 days, but use 78 lb salt per month. A 1.5 cubic ft softener would be small. It would regen every 4-5 days which, when you have chlorinated city water, is hard on the softener resin. I don't recommend it. Carbon filtration to remove chlorine: This is not necessary, but some people object to the chlorine, so it is up to you. If your water guy is suggesting a softener with carbon in the softener (your description was unclear) don't do it - you will damage your softener resin. A properly sized carbon filter will cause minimal pressure drop. A carbon filter that is too small will cause high pressure drop. A carbon filter can be either in the form of a cartridge filter where you change the cartridge every six months, or a larger media-bed filter (it will look like a softener, but won't need to regen, just backwash). Regardless of where you choose to obtain your softener, you want the following for an industry standard softener. If you are looking for a non-electronic softener, Kinetico offers the more reliable options at a premium price (and you would need to deal with a local Kinetico rep). Any decent softener vendor should be able to provide the following: High quality American or German made resin. This will provide a tight size distribution for optimal flow within the resin Since you have CITY WATER: 10% crosslinked resin. The oxidizers that city water treatment plants use, such as chlorine or chloramine, are harmful to softener resins. Higher crosslinking will resist chemical attack longer. Top basket. This serves two purposes. It sets up a proper water distribution during normal operation and prevents resin loss during backwash. Gravel underbed. The gravel underbed is there to set up proper flow patterns, improve backwash, keep the bottom basket in place, prevent basket failure, and prevent...

Bear in mind that when you do add a neutralizer the hardness of the water will rise. With higher hardness the correct sizing of the softener may change. You are kind of in the middle between the correct size for the water conditions (PH not withstanding) and water use and your "potential for peak flow rate to reach above 9 gpm" which you have not proven which a 1 cu ft softener with hi-cap standard 8% resin should accommodate. If it were me I install an acid neutralizer and then test the hardness over a period of time. Then correctly size the softener and be done with it. Even with the small amount of iron you have (you didn't mention any manganese) you'll want to use Iron Out or the like routinely and 8 days between regen with any iron is too long. In a 1 cu ft softener the advantages you see in the SST-60 lit will be negligible to none.

SFR = service flow rate. Bypass your existing softener. Using the bathtub as the measuring point, open BOTH the hot and cold water faucets completely open. If your tub has a single faucet then find a hose bib near the water entrance to the home and use that. Place a 1 gallon container under the faucet and measure the amount of time it takes to fill the container in seconds. Year old water quality reports with results in ranges is hardly conductive to accurately sizing your softener. Since you're wanting to treat the water at your house that's where water samples should be taken and that's what should be tested.

As you noted... sizing a softener is based on mathematics. Arriving at the correct answer (correct softener size) is based on the data inputted into a mathematical formula. Using average numbers or numbers from a water quality report taken at the treatment plant before the water travels through the system and finally arrives at your water meter usually results in an incorrectly sized softener and/or not treating other water conditions that you have not noted since you only mentioned hardness. There's more to treating water than just the hardness. We need to know hardness, pH, iron, manganese, TDS, chlorine, sodium, arsenic. for starters and we need to know exact numbers. The way to get that data is from a test done (preferably) by a certified lab of the water in your home. How many bathrooms and do you have any high water use appliances like a Jacuzzi or super shower? You don't want a turbulator or Vortech tank. If you want to calculate the softener size based on what you posted then just average out the results you've already gotten and just pick one. I won't help you size a softener incorrectly or validate your choice in doing it wrong. This post was edited by justalurker on Thu, Sep 5, 13 at 15:25